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New Sustainable Hunting Quotas Could Improve Lion Numbers

Not long ago, an American hostess published a photo of her hunting lion on the Internet, evoking a lot of disputes. Recently, researchers from Imperial College London, University of Stirling and University of Cape Town noted that if the hunting quotas of lions are reasonably set, the sustainable hunting can help grow lion population. The result has been published on Proceedings of the National Academy of Sciences.

Sport hunting is always in controversy. “Many people don’t feel happy about the idea of hunting animals for sport, especially animals that are as impressive and beautiful as lions.” Professor E.J. Milner-Gulland, an author of the study from the Department of Life Sciences at Imperial College London, said:” However, in some cases, the money that comes from hunting is what enables the land to be set aside for wildlife and this provides the lions with a home.” Hunters have to pay up to US$125,000 to shoot a male lion. The money enables governments to leave wilderness areas as habitats for wildlife instead of turning the land over for other purposes such as farming.

However, the hunting quotas are determined by the governments and there is no formal mechanism or reliable information to help decide sustainable hunting quotas. In undeveloped countries, the quotas for sport hunting are sometimes too high to keep reasonable number of wildlife. This has contributed to a decrease in the amount of lions across Africa, from an estimated 100,000 fifty years ago to approximately 30,000 today. Unfortunately, this unsustainable hunting management has not yet been improved significantly.

 An image of lions in the Serengeti National Park, Tanzania.

An image of lions in the Serengeti National Park, Tanzania. *Image source: Nils Bunnefeld

The good news is that hunting managers are now taking more and more factors into consideration based on the current situation. Tanzania and Mozambique have already set limitations on the minimum age that can be hunted. Since male lions are sexually active at their four, studies have proved that hunting male adults older than six would not influence the sustainable population growth of lions. Although only considering one factor is not sufficient for setting a sustainable hunting quota mechanism, finally people are making some progress.

In the new study, researchers devised a method that can ensure more sustainable hunting quotas. The algorithm mainly considers the observation upon lions, the management and execution of quotas, as well as the dynamic changes in lion numbers. Through analyzing on how long it takes to find and shoot a lion in a given area, researchers are able to use this algorithm to estimate how many adult males can be hunted while allowing the lion population to grow.

In practice, the researchers modelled the effects of introducing their new method for setting hunting quotas in a heavily depleted lion population and discovered that the amount of adult males would grow from about 38 to 100 individuals in 30 years. During this time period, the sustainable quota can increase from 15 to 22 lions. Therefore, if the model functions in good accordance with reality, then governments could use this model to benefit hunters while absorb funds to allow lion population to grow – a win-win scenario.

Number of adult male lions

This figure shows the changes in the number of adult males older than 4 and the number that can be hunted. The shadow area is the number change interval related with the uncertainties resulting from different factors. *Image source: Charles T. T. Edwards,et al.(2013)PNAS.

 “As conservation scientists, we want to make sure that populations of lions can thrive while sport hunting is permitted – this requires to set hunting quotas at the right level.” Professor Milner-Gulland added:” Our new method for setting rational quotas relies on information that is easy for governments to get hold of and it should be simple for them to implement.” He said that their next move is to test the method in the field. “If it proves successful, we hope this method can be widely adopted in conservation for other animals which are hunted by searching for individuals, such as wild sheep or deer.”